The present invention relates to an electroluminescent lighting device that is elongate and flexible for use in various lighting applications.
Electroluminescent lighting devices are known. These typically have a multi-layered structure including, for example, an indium tin oxide layer deposited on a substrate. A layer containing phosphorus or similar material may cover this. An additional dielectric layer may overlie the phosphorus layer, which is typically a barium titanium oxide layer such as barium titanate.
The structure may further include a conductive layer of silver ink, carbon or the like for the conduction of electrical current and, finally, an insulating transparent or translucent outermost plastic layer or the like for protection.
Upon the passage of an alternating or pulsating direct current through the layers, including the indium tin oxide and silver ink or carbon layers, there is a general migration of electrons that release energy as light during the process. The released light can be emitted through surrounding layers to provide light from the devices as a whole.
Although such devices have been around for many years, they have generally been used as back-lights for illuminating signs on a rigid support. Although devices in a flexible cable form is also known, for example as disclosed in U.S. Pat. No. 5,485,355, their constructions that enable the conduction of electrical current are found to be complicated and/or unreliable.
The invention seeks to mitigate or to at least alleviate such problems by providing an improved electroluminescent lighting device.
According to one aspect of the invention, there is provided an electroluminescent lighting device comprising an elongate flexible body having an inner part and an outer part, said outer part being of light-transmissive material, an elongate multi-layer electroluminescent element including a pair of co-extending conductive regions and extending along the inner body part, a pair of elongate conductors extending along the inner body part for supplying electrical power to the electroluminescent element, said conductors being separated from the electroluminescent element by at least a portion of the inner body part, and a plurality of flexible contact elements located at intervals along the inner body part for electrically connecting the conductive regions of the electroluminescent element to the conductors, each said contact element having a first part in contact with a respective said conductive region and a second part extending through said portion of the inner body part and contacting a respective said conductor.
Preferably, the electroluminescent element is supported by the inner body part.
More preferably, the inner body part is formed with a channel holding the electroluminescent element therein.
Further more preferably, the channel has an open side having a reduced width which is smaller than the width of the electroluminescent element.
It is preferred that the electroluminescent element has a flat cross-section and opposite edges, along which edges the conductive regions extend respectively in a continuous manner.
Preferably, the conductors are embedded within the inner body part.
It is preferred that the conductors are provided by respective stranded metal wires.
In one preferred embodiment, the flexible contact elements are formed as conductive resilient inserts.
Preferably, at least some of the inserts are of conductive rubber.
In another preferred embodiment, at least some of the flexible contact elements are formed of wire.
Preferably, the wires are soldered to the elongate conductors.
Preferably, the wires are clipped through the conductive regions of the electroluminescent element.
According to another aspect of the invention there is provided a method of forming the above-disclosed electroluminescent lighting device, the method comprising: cutting a plurality of access cavities in the inner body part, inserting a conductive rubber piece into each cavity to come into contact with one of said elongate conductors and installing the electroluminescent element into the inner body part so that each of said elongate conductors and one of said conductive regions of the electroluminescent element comes into contact with one or more of said conductive rubber pieces. In yet a further aspect of the invention there is provided a method of forming the above-disclosed electroluminescent lighting device, the method comprising: taking the inner body part and cutting a plurality of access cavities therein to expose portions of each elongate conductor and said conductive regions, the method further comprising attaching respective pieces of flexible wire to each exposed portion of each elongate conductor and attaching each piece of flexible wire to a corresponding exposed portion of the respective conductive region.
It is further preferred that the outer body part is extruded onto the inner body part to form the complete electroluminescent lighting device.
According to another aspect of the invention, there is provided an electroluminescent lighting device comprising:
an elongate flexible body of light-transmissive material,
an elongate multi-layer electroluminescent element extending along and/or within the body and including a pair of co-extendsive elongate conductive regions,
a pair of elongate conductors extending along and within the body for supplying electrical power to the electroluminescent element, and
wherein each elongate conductor provides electrical power to the electroluminescent element via a respective one of said conductive regions throughout the length of the electroluminescent lighting device.
Preferably each said elongated conductor is attached to a respected said conductive region by electrically conductive glue.
Preferably the conductive glue is flexible.
Alternatively each said elongate conductor is in direct contact with a respective said conductive region.
Preferably, the device is formed as a co-extrusion wherein the body, electroluminescent strip and the elongate conductors are extruded simultaneously.
Preferably be conductive glue is co-extruded with the device.
It is preferred that the electroluminescent element has a flat cross-section and opposite edges, along which edges the conductive regions extend respectively in a continuous manner.
It is preferred that the conductors are provided by respective metal strips of rectangular cross-section.
Preferably the metal strips are of copper.
It might be desirable to provide an electroluminescent lighting device having a form of xe2x80x9cchasing-effectxe2x80x9d. To this end, a third optional elongated conductor can be positioned in between said pair of elongate conductors, so as to provide three elongate conductors extending along and within the body. These three conductors might receive a specially controlled power supply to achieve a changing or chasing visual effect in the electroluminescent device.
The third elongate conductor might be connected to another conductive region of the electroluminescent strip, or might be connected by wires to one of the regions associated with the pair of conductors.
As an alternative, the third conductor might be associated with a different layer of the electroluminescent strip.
Where the third elongate conductor is associated with a conductive region in between the conductive regions that are associated with said pair of elongate conductors, conductive glove might be provided between the third elongate conductor and that conductive region.
Alternatively, the third elongate conductor might be in direct contact with the third conductive region.